Narrow-linewidth surface-emitting distributed feedback semiconductor lasers with low threshold current

Surface emitting distributed feedback (SE-DFB) semiconductor laser has become one of study hotspots due to its narrow linewidth and high power. Herein, a SE-DFB semiconductor laser is proposed based on second-order Bragg grating for feedback and out-coupling. The grating is fabricated on the confinement layer, which can realize the laser emission from the substrate and avoid the secondary epitaxial growth. The asymmetric waveguide structure is introduced into the device to increase the probability of photon and grating interaction while reducing the threshold current. The results show that when the current is 3A, the output laser power from the substrate achieves 1.22 W. In the meantime, the threshold current, voltage and slope efficiency are 300 mA, 1.73 V and 0.45 W/A, respectively. The center wavelength is 980.1 nm and the linewidth is 0.84 nm. This work has important implications for low threshold current narrow linewidth SE-DFB semiconductor lasers.